scholarly journals Entanglement, partial set of measurements, and diagonality of the density matrix in the parton model

2021 ◽  
Author(s):  
Vladimir Skokov
Keyword(s):  
Density Matrix ◽  
Parton Model

scholarly journals Entanglement, partial set of measurements, and diagonality of the density matrix in the parton model

2020 ◽  
Vol 101 (3) ◽  
Author(s):  
Haowu Duan ◽  
Candost Akkaya ◽  
Alex Kovner ◽  
Vladimir V. Skokov
Keyword(s):  
Density Matrix ◽  
Parton Model

scholarly journals Quantum information approach to high energy interactions

2021 ◽  
Vol 380 (2216) ◽  
Author(s):  
Dmitri E. Kharzeev
Keyword(s):  
Density Matrix ◽  
Light Cone ◽  
Particle Physics ◽  
Evolution Equations ◽  
Spin Asymmetry ◽  
Entanglement Entropy ◽  
Parton Model ◽  
High Energy ◽  
Wave Functions ◽  
Fock State

High energy hadron interactions are commonly described by using a probabilistic parton model that ignores quantum entanglement present in the light-cone wave functions. Here, we argue that since a high energy interaction samples an instant snapshot of the hadron wave function, the phases of different Fock state wave functions cannot be measured—therefore the light-cone density matrix has to be traced over these unobservable phases. Performing this trace with the corresponding U ( 1 ) Haar integration measure leads to ‘Haar scrambling’ of the density matrix, and to the emergence of entanglement entropy. This entanglement entropy is determined by the Fock state probability distribution, and is thus directly related to the parton structure functions. As proposed earlier, at large rapidity η the hadron state becomes maximally entangled, and the entanglement entropy is S E ∼ η according to QCD evolution equations. When the phases of Fock state components are controlled, for example in spin asymmetry measurements, the Haar average cannot be performed, and the probabilistic parton description breaks down. This article is part of the theme issue ‘Quantum technologies in particle physics’.

Density matrix and rate equation analyses for picosecond pump/probe combustion diagnostics

AIAA Journal ◽  
1999 ◽  
Vol 37 ◽  
pp. 723-731
Author(s):  
Thomas Settersten ◽  
Mark Linne ◽  
James Gord ◽  
Gregory Feichtner
Keyword(s):  
Density Matrix ◽  
Rate Equation ◽  
Pump Probe ◽  
Combustion Diagnostics

PARTON DISTRIBUTION FUNCTIONS AND THE QCD-IMPROVED PARTON MODEL — AN OVERVIEW

1987 ◽  
Vol 02 (04) ◽  
pp. 1369-1387 ◽  
Author(s):  
Wu-Ki Tung
Keyword(s):  
Parton Distribution ◽  
Particle Production ◽  
Heavy Particle ◽  
Parton Model ◽  
Distribution Functions ◽  
Collider Physics ◽  
Parton Distribution Functions ◽  
Parton Distributions ◽  
First Order ◽  
Small X

Some non-trivial features of the QCD-improved parton model relevant to applications on heavy particle production and semi-hard (small-x) processes of interest to collider physics are reviewed. The underlying ideas are illustrated by a simple example. Limitations of the naive parton formula as well as first order corrections and subtractions to it are dis-cussed in a quantitative way. The behavior of parton distribution functions at small x and for heavy quarks are discussed. Recent work on possible impact of unconventional small-x behavior of the parton distributions on small-x physics at SSC and Tevatron are summarized. The Drell-Yan process is found to be particularly sensitive to the small x dependence of parton distributions. Measurements of this process at the Tevatron can provide powerful constraints on the expected rates of semi-hard processes at the SSC.

Density matrix and purity evolution in dissipative two-level systems: II. Relaxation

2021 ◽  
Author(s):  
Sambarta Chatterjee ◽  
Nancy Makri
Keyword(s):  
Density Matrix ◽  
Time Evolution ◽  
Reduced Density Matrix ◽  
Level System ◽  
Two Level Systems ◽  
Reduced Density ◽  
Harmonic Bath

We investigate the time evolution of the reduced density matrix (RDM) and its purity in the dynamics of a two-level system coupled to a dissipative harmonic bath, when the system is initially placed in one of its eigenstates.

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